Update GitHub workflow to use Java 17 for Grails 7 compatibility

Author: fdevans

.github/workflows/gradle.yml

@@ -14,10 +14,10 @@ jobs:
       - name: Get Fetch Tags
         run: git -c protocol.version=2 fetch --tags --progress --no-recurse-submodules origin
         if: "!contains(github.ref, 'refs/tags')"
-      - name: Set up JDK 1.8
+      - name: Set up JDK 17.8
         uses: actions/setup-java@v1
         with:
-          java-version: 1.8
+          java-version: 17
       - name: Grant execute permission for gradlew
         run: chmod +x gradlew
       - name: Build with Gradle